Class Notes (1,100,000)
CA (630,000)
Western (60,000)
BIOL (7,000)
Lecture

Hibernation - Guest Lecture study guide that includes all the notes and relevant pictures from lecture as well as additional notes from the assigned readings


Department
Biology
Course Code
BIOL 2601A/B
Professor
Brent Sinclair

This preview shows pages 1-2. to view the full 8 pages of the document.
Organismal Phys Lecture 14
Hibernation
Organisms that Hibernate
Phylogenetically, many different orders can hibernate
Hibernation is an ancestral feature; some orders have lost this feature
Larger animals tend not to hibernate; small animals more likely to
It is questionable whether bears hibernate “winter lethargy”
Monotremata, marsupialia, pholidota, rodentia, primates, chiroptera, insectivore, carnivores,
and dermoptera; in each of these at least one member hibernates
Food Availability and Metabolizing Fat
Mammals and birds are endothermic (use their metabolism as a source of heat) homeotherms
(maintain a constant body temperature)
Where C’ is thermal conductance
When it’s cold outside:
o Mammals will become less thermally conductive (better insulated) - ↓value of C
o Will increase their metabolic rate (burn more energy generate more heat)
this diagram just shows
that during the winter months,
food is relatively unavailable and
therefore energy is scarce
During the summer
months, food availability is high,
and the metabolic rate is close to
BMR because the animal doesn’t
need to keep itself warm
(therefore won’t need to expend
energy)
Animals can’t store food
because:
1. Will spoil
2. Other animals will
steal it
3. Where to put it

Only pages 1-2 are available for preview. Some parts have been intentionally blurred.

Metabolizing Fat Example
Assume mean winter temperature is 10°C.
At 10°C, MR = 4 mL O2 / g/ hr
Therefore, MR = 400 mL O2 / hr for whole animal
= 0.4 L O2 / hr for whole animal
Assume winter lasts for 100 days (approx. 3 ½ months)
24 hrs/day X 100 days = 2400 hours
Therefore, over the entire winter, the whole animal consumes 960L O2
1 L O2 corresponds to 5 kcal of energy consumed
Therefore, over the entire winter, the whole animals consumes 4800kcal of energy
1 g of fat contains 9kcal of energy
Therefore, over the entire winter, the animal needs to metabolize 533g of fat!
That’s 533% more body mass!
Hibernators Do ‘Deposit’ Fat during Summer
o You can’t store up ALL the energy you need; mammals, before hibernation, will prepare by
putting on approximately 100g of mass
o But what about the other 400g?
o notice the spikes in food
consumption right before
hibernation occurs
You're Reading a Preview

Unlock to view full version

Only pages 1-2 are available for preview. Some parts have been intentionally blurred.

4 Phases of Repetitive Hibernation
cycle will occur all winter
Animals will let their body temperature fall
closer to ambient temperature; therefore the
100g of fat will probably last the whole winter
Torpor: body temp is low and constant
Arousal : body temp rises
Interbout Euthermia: lasts about 24 hours
Entrance: drop in body temperature back
down to Torpor
Physiological Changes That Occur Before and During Hibernation
Animals will fatten up! (but not all fat is
equal)
Saturated fatty acids have no carbon-
carbon double bonds
Monounsaturated fats have one C=C
double bond
Polyunsaturated fats (PUFA) have
multiple (2+) C=C double bonds
How much of each kind of fat an animal
eats affects its hibernation
All PUFAs animal acquires will be through diet (because unlike plants, can’t synthesize them;
therefore will need to be picky eaters)
Before hibernating, animals will forage in order to attain an intermediate level of PUFAs (ideal)
As graphs show, most animals will hibernate when they have an intermediate level of PUFAs and
will also have the longest Torpor bout length (makes sense, you want this to be longer because
then you save more energy)
First graph also shows that intermediate level of PUFAs are associated with the lowest body
temperature and metabolic rate during hibernation
o
o
o
You're Reading a Preview

Unlock to view full version